摘要
The relationship between conformation change and activity of E. coli L-asparaginase hasbeen studied with circular dichroism spectra and microcaloric methods. In many papers [1-4],it has been pointed out that the active site of L-asparaginase isclosely related to tyrosyl residues. The present authors[5] have studied the effects of L-cysteine on the activity and the conformation of L-asparaginase with UV difference spectraand kinetic methods. Moreover, we have studied the space arrangement of tyrosyl residuesin the enzyme molecule. The results show that every enzyme molecule contains about 56 tyrosylresidues,20 of which are in the hydrophobic core of the enzyme molecule, another 20 at thesurface of the enzyme molecule, and the rest in the rifts and hollows of the enzyme molecule.Meanwhile, further study has also been made to determine the relationship between the changesof the enzyme activity and the ionization of tyrosyl residues as well as their chemical modifica-tion. By Zou Chenglu’s graphical method we have proved that two tyrosyl residues at thesurface of the enzyme molecule are the essential groups.
The relationship between conformation change and activity of E. coli L-asparaginase hasbeen studied with circular dichroism spectra and microcaloric methods. In many papers ^([1-4]),it has been pointed out that the active site of L-asparaginase isclosely related to tyrosyl residues. The present authors~[5] have studied the effects of L-cysteine on the activity and the conformation of L-asparaginase with UV difference spectraand kinetic methods. Moreover, we have studied the space arrangement of tyrosyl residuesin the enzyme molecule. The results show that every enzyme molecule contains about 56 tyrosylresidues,20 of which are in the hydrophobic core of the enzyme molecule, another 20 at thesurface of the enzyme molecule, and the rest in the rifts and hollows of the enzyme molecule.Meanwhile, further study has also been made to determine the relationship between the changesof the enzyme activity and the ionization of tyrosyl residues as well as their chemical modifica-tion. By Zou Chenglu's graphical method we have proved that two tyrosyl residues at thesurface of the enzyme molecule are the essential groups.
